This invention relates to a bending tool for bending workpieces, especially plate and sheet metal blanks, along a bending line, with at least one bending element positioned on one side of the workpiece and with at least one retaining device featuring clamping elements on mutually opposite sides in the transverse direction of the workpiece so that a relative movement of the clamping elements on both sides in the transverse direction of the workpiece permits the workpiece to be clamped down on the retaining device, while the retaining device with the clamped-on workpiece and a bending element can be moved toward each other in a bending stroke that bends the workpiece. This bending stroke includes a component in the bending-stroke direction extending in the transverse direction of the workpiece as well as a component in the cross stroke direction that extends transversely relative to the plane bounded by the direction of the bending line and the bending-stroke direction, the directional movement of the bending stroke being controlled by means of a motion control system that encompasses at least one control element associated and moving with a bending element as well as at least one guide element associated with a bending element. This invention also relates to a bending machine that is equipped with at least one such bending tool.
A bending tool and a bending machine of the type referred to above have been described in JP 59 033032 A. This earlier bending tool includes an upper tool section positioned above the workpiece to be processed as well as a lower tool section positioned underneath the workpiece to be processed. The upper tool section encompasses a spring-loaded retaining plate which in its home position extends in the transverse direction of the workpiece, and, to the side of that plate, a bending tool.
The bending tool can be rotated around a pivot that extends parallel to the bending line along the workpiece that is to be bent and is provided with a control surface that is sloped in the transverse direction of the workpiece. The lower tool section consists essentially of a support block positioned opposite the retaining plate of the upper tool section, as well as a control block positioned to the side of and at a distance from the support block. On its side facing the bending tool of the upper tool section, the control block on its part features a sloped control surface. A metal blank to be processed is placed on the support block of the lower tool section. Next, the upper tool section is lowered toward the lower tool section in the transverse direction of the workpiece. This causes the retaining plate of the upper tool section to make contact with the surface of the metal blank facing it. The blank is thus clamped between the retaining plate of the upper tool section and the support block of the lower tool section. As the downward movement of the upper tool section continues, the retaining plate remains firmly in place. The bending tool of the upper tool section, however, continues to move in the direction of the lower tool section. As a result, the forming edge of the bending tool strikes the rim of the blank laterally protruding between the retaining plate of the upper tool section and the support block of the lower tool section. At the same time the control surface of the bending tool makes contact with the control surface of the control block on the lower tool section. As they come together, the two control surfaces cause the downwardly moving bending tool to rotate around its pivot. The overall result is a bending stroke of the bending punch with a component in the transverse direction of the workpiece and a component parallel to the workpiece.
It is the objective of this invention to provide a novel bending tool design that simplifies the prior art construction described above.